A bidirectional memory cell includes a write unit and a read unit. The write unit and the read unit each include an MTJ structure having a first and second pinned layers and a free layer. The first and second pinned layers are separated from the free layer by at least one tunnel barrier. The first pinned layer is electrically coupled to a first write line through a first diode. The second pinned layer is electrically connected to a second word line through a second diode. The free layer is electrically coupled to a first bit line. Additionally, the free layer of the read unit is magnetically coupled to the free layer of the write unit.
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1. A bidirectional memory unit, comprising: a free magnetic layer electrically coupled to a bit line; a first pinned magnetic layer and a second pinned magnetic layer separated from the free magnetic layer by at least one tunnel barrier layer; a first diode comprising an anode and a cathode, the anode of the first diode being coupled to a first word line and the cathode of the first diode being electrically coupled to the first pinned magnetic layer; and a second diode comprising an anode and a cathode, the anode of the second diode being electrically coupled to the second pinned magnetic layer and the cathode of the second diode being electrically coupled to a second word line.
A memory cell that can store data based on the magnetic orientation of its components. It includes a "free" magnetic layer connected to a bit line. Two "pinned" magnetic layers sandwich the free layer, separated by thin tunnel barrier layers. A first diode connects the first pinned layer to a first word line; when the diode is forward biased (turned on), current can flow to the pinned layer. Similarly, a second diode connects the second pinned layer to a second word line, enabling current flow when forward biased. The diodes control writing data to the free layer by changing its magnetic orientation.
2. The bidirectional memory unit according to claim 1 , wherein the bidirectional memory unit is a radially arranged memory unit, and wherein the first pinned magnetic layer and the second pinned magnetic layer are separated from the free magnetic layer by a single tunnel barrier layer.
This memory cell, described in the previous memory cell description, has a radial arrangement. This means the pinned layers and free layer are arranged in a way that allows for a single tunnel barrier between each pinned layer and the free layer.
3. The bidirectional memory unit according to claim 2 , wherein the first pinned magnetic layer and the second pinned magnetic layer are on a same side of the single tunnel barrier layer from the free magnetic layer.
In this radial memory cell, as described in the previous radial memory cell description, both pinned magnetic layers are located on the same side of the single tunnel barrier layer relative to the free magnetic layer.
4. The bidirectional memory unit according to claim 2 , wherein the bidirectional memory unit is a write unit or a read unit.
The radial memory cell, as described in the previous radial memory cell description, can function as either a write unit (used to store data) or a read unit (used to retrieve data).
5. The bidirectional memory unit according to claim 4 , wherein the memory unit comprises a read unit, and wherein a state of the free magnetic layer is detected by sensing a voltage at the free magnetic layer if the first and second diodes are forward biased.
This memory unit, based on the previous description of a write or read unit, is a read unit. To determine the stored data (magnetic state) of the free layer, the system measures the voltage at the free layer when both the first and second diodes are forward biased, allowing current to flow.
6. The bidirectional memory unit according to claim 1 , wherein the bidirectional memory unit is an axially arranged memory unit, and wherein the first pinned magnetic layer is separated from the free magnetic layer by a first tunnel barrier layer and the second pinned magnetic layer is separated from the free magnetic layer by a second tunnel barrier layer.
The memory cell, as described in the initial memory cell description, has an axial arrangement. In this arrangement, the first pinned magnetic layer is separated from the free magnetic layer by one tunnel barrier layer, and the second pinned magnetic layer is separated from the free magnetic layer by a second, distinct tunnel barrier layer.
7. The bidirectional memory unit according to claim 6 , wherein the first pinned magnetic layer and the second pinned magnetic layer are on opposite sides of the free magnetic layer.
In this axially arranged memory cell, as described in the previous axial arrangement description, the first and second pinned layers are located on opposite sides of the free layer.
8. The bidirectional memory unit according to claim 6 , wherein the bidirectional memory unit is a write unit or a read unit.
This axially arranged memory cell, based on the previous axial arrangement description, can function as either a write unit (used to store data) or a read unit (used to retrieve data).
9. The bidirectional memory unit according to claim 8 , wherein the memory unit comprises a read unit, and wherein a state of the free magnetic layer is detected by sensing a voltage at the free magnetic layer if the first and second diodes are forward biased.
This memory unit, based on the previous description of a write or read unit, is a read unit. To determine the stored data (magnetic state) of the free layer, the system measures the voltage at the free layer when both the first and second diodes are forward biased, allowing current to flow.
10. The bidirectional memory unit according to claim 1 , wherein the bidirectional memory unit is a write unit of a bidirectional memory cell, the bidirectional memory cell further comprising a read unit, the read unit comprising: a second free magnetic layer electrically coupled to a second bit line and magnetically coupled to the free magnetic layer of the write unit; a third pinned magnetic layer and a fourth pinned magnetic layer separated from the second free magnetic layer by at least one second tunnel barrier layer; a third diode comprising an anode and a cathode, the anode of the third diode being coupled to a third word line and the cathode of the third diode being electrically coupled to the third pinned magnetic layer; and a fourth diode comprising an anode and a cathode, the anode of the fourth diode being electrically coupled to the fourth pinned magnetic layer and the cathode of the second diode being electrically coupled to a fourth word line.
The memory unit, as described in the initial memory cell description, is specifically a write unit. It is part of a larger bi-directional memory *cell* that also includes a read unit. The read unit has its own "free" magnetic layer magnetically linked to the write unit's free layer, and connected to its own bit line. This read unit also has two pinned magnetic layers, separated from its free layer by tunnel barriers, and connected to respective word lines through two more diodes.
11. The bidirectional memory unit according to claim 10 , wherein the write unit and the read unit are radially arranged memory units, wherein the first pinned magnetic layer and the second pinned magnetic layer are separated from the free magnetic layer of the write unit by a first tunnel barrier layer, and wherein the third pinned magnetic layer and the fourth pinned magnetic layer are separated from the second free magnetic layer of the read unit by a second tunnel barrier layer.
In this bidirectional memory cell, based on the previous description with separate write and read units, both the write and read units have a radial arrangement. This means that in the write unit, the pinned layers are separated from the free layer by a single tunnel barrier. Similarly, in the read unit, its pinned layers are separated from its free layer by its own single tunnel barrier.
12. The bidirectional memory unit according to claim 10 , wherein the write unit and the read unit are axially arranged memory units, wherein the first pinned magnetic layer is separated from the free magnetic layer of the write unit by a first tunnel barrier layer and the second pinned magnetic layer is separated from the free magnetic layer of the write unit by a second tunnel barrier layer, and wherein the third pinned magnetic layer is separated from the second free magnetic layer of the read unit by a third tunnel barrier layer and the fourth pinned magnetic layer is separated from the second free magnetic layer of the read unit by a fourth tunnel barrier layer.
In this bidirectional memory cell, based on the previous description with separate write and read units, both the write and read units have an axial arrangement. This means that in the write unit, one pinned layer is separated from its free layer by one tunnel barrier, and the other pinned layer is separated by a second tunnel barrier. Similarly, in the read unit, one pinned layer is separated from its free layer by one tunnel barrier, and the other pinned layer is separated by a second tunnel barrier.
13. A bidirectional memory cell, comprising: a write unit and a read unit, the write unit comprising: a first free magnetic layer electrically coupled to a first bit line; a first pinned magnetic layer and a second pinned magnetic layer separated from the first free magnetic layer by at least one write-unit tunnel barrier layer; a first diode comprising an anode and a cathode, the anode of the first diode being coupled to a first word line and the cathode of the first diode being electrically coupled to the first pinned magnetic layer; and a second diode comprising an anode and a cathode, the anode of the second diode being electrically coupled to the second pinned magnetic layer and the cathode of the second diode being electrically coupled to a second word line; and the read unit comprising: a second free magnetic layer electrically coupled to a second bit line and magnetically coupled to the first free magnetic layer of the write unit; a third pinned magnetic layer and a fourth pinned magnetic layer separated from the second free magnetic layer by at least one read-unit tunnel barrier layer; a third diode comprising an anode and a cathode, the anode of the third diode being coupled to a third word line and the cathode of the third diode being electrically coupled to the third pinned magnetic layer; and a fourth diode comprising an anode and a cathode, the anode of the fourth diode being electrically coupled to the fourth pinned magnetic layer and the cathode of the second diode being electrically coupled to a fourth word line.
A bidirectional memory cell that has two units: a write unit and a read unit. The write unit includes a free magnetic layer connected to a bit line, two pinned magnetic layers separated from the free layer by tunnel barriers, and two diodes connecting the pinned layers to word lines. The read unit includes its own free magnetic layer (magnetically linked to the write unit's free layer and connected to a separate bit line), two more pinned layers separated from its free layer by tunnel barriers, and two more diodes connecting these pinned layers to separate word lines.
14. The bidirectional memory cell according to claim 13 , wherein the write unit and the read unit are radially arranged memory units, wherein the first pinned magnetic layer and the second pinned magnetic layer are separated from the first free magnetic layer of the write unit by a single write-unit tunnel barrier layer, and wherein the third pinned magnetic layer and the fourth pinned magnetic layer are separated from the second free magnetic layer of the read unit by a single read-unit tunnel barrier layer.
This bidirectional memory cell, as described in the previous bidirectional memory cell description, has both the write and read units radially arranged. This means that in the write unit, a single tunnel barrier separates each pinned layer from its free layer, and the same single-barrier separation applies to the pinned and free layers in the read unit.
15. The bidirectional memory unit according to claim 13 , wherein the write unit and the read unit are axially arranged memory units, wherein the first pinned magnetic layer is separated from the first free magnetic layer of the write unit by a first write-unit tunnel barrier layer and the second pinned magnetic layer is separated from the first free magnetic layer of the write unit by a second write-unit tunnel barrier layer, and wherein the third pinned magnetic layer is separated from the second free magnetic layer of the read unit by a first read-unit tunnel barrier layer and the fourth pinned magnetic layer is separated from the second free magnetic layer of the read unit by a second read-unit tunnel barrier layer.
This bidirectional memory cell, as described in the earlier bidirectional memory cell description, has both the write and read units axially arranged. This means each pinned layer in the write unit is separated from its free layer by a different tunnel barrier layer, and similarly, each pinned layer in the read unit is separated from its free layer by a different tunnel barrier layer.
16. The bidirectional memory unit according to claim 13 , wherein a state of the second free magnetic layer is detected by sensing a voltage at the second free magnetic layer if the third and fourth diodes are forward biased.
In this bidirectional memory cell, as described in the earlier bidirectional memory cell description, the data stored in the read unit's free layer is determined by measuring the voltage at that free layer when its two associated diodes are forward biased.
17. A bidirectional memory cell, comprising: a write unit and a read unit, the write unit comprising a first magnetic tunnel junction (MTJ) structure comprising a first pinned magnetic layer, a first free magnetic layer and a second pinned magnetic layer, the first and second pinned magnetic layers being separated from the first free magnetic layer by at least one write-unit tunnel barrier layer, the first pinned magnetic layer being electrically coupled to a first write line through a first diode comprising an anode and cathode, the anode of the first diode being electrically connected to the first word line and the cathode of the first diode being electrically connected to the first pinned magnetic layer, the second pinned magnetic layer being electrically connected to a second word line through a second diode comprising an anode and a cathode, the anode of the second diode being electrically connected to the second pinned magnetic layer and the cathode of the second diode being electrically connected to the second word line, the first free magnetic layer being electrically coupled to a first bit line; and the read unit comprising a second MTJ structure comprising a third pinned magnetic layer, a second free magnetic layer and a fourth pinned magnetic layer, the third and fourth pinned magnetic layers being separated from the second free magnetic layer by at least one read-unit tunnel barrier layer, the third pinned magnetic layer being electrically coupled to a third write line through a third diode comprising an anode and cathode, the anode of the third diode being electrically connected to the third word line and the cathode of the third diode being electrically connected to the third pinned magnetic layer, the fourth pinned magnetic layer being electrically connected to a fourth word line through a fourth diode comprising an anode and a cathode, the anode of the fourth diode being electrically connected to the fourth pinned magnetic layer and the cathode of the fourth diode being electrically connected to the fourth word line, the second free magnetic layer being electrically coupled to a second bit line and being magnetically coupled to the first free magnetic layer.
This bidirectional memory cell consists of a write unit and a read unit, each employing a Magnetic Tunnel Junction (MTJ) structure. The write unit has a free magnetic layer between two pinned magnetic layers, separated by tunnel barriers. Diodes connect the pinned layers to word lines and the free layer to a bit line for writing data. The read unit mirrors this MTJ structure, also with a free layer (magnetically coupled to the write unit's free layer), pinned layers separated by tunnel barriers, diodes connected to word lines, and a free layer connected to a bit line. The diodes on both the write and read units enable addressing and controlling the magnetic state of the free layers for data storage and retrieval.
18. The bidirectional memory cell according to claim 17 , wherein the write unit and the read unit are radially arranged memory units, wherein the first pinned magnetic layer and the second pinned magnetic layer are separated from the first free magnetic layer by a single write-unit tunnel barrier layer, and wherein the third pinned magnetic layer and the fourth pinned magnetic layer are separated from the second free magnetic layer by a single read-unit tunnel barrier layer.
This bidirectional memory cell, described in the previous memory cell description consisting of a write and read unit, has both units arranged radially. Therefore, in each unit (write and read), a single tunnel barrier separates each pinned layer from its free layer.
19. The bidirectional memory unit according to claim 17 , wherein the write unit and the read unit are axially arranged memory units, wherein the first pinned magnetic layer is separated from the first free magnetic layer by a first write-unit tunnel barrier layer and the second pinned magnetic layer is separated from the first free magnetic layer by a second write-unit tunnel barrier layer, and wherein the third pinned magnetic layer is separated from the second free magnetic layer by a first read-unit tunnel barrier layer and the fourth pinned magnetic layer is separated from the second free magnetic layer by a second read-unit tunnel barrier layer.
This bidirectional memory cell, as described in the previous memory cell description consisting of a write and read unit, has both units arranged axially. Therefore, in each unit, one pinned layer is separated from its free layer by one tunnel barrier, and the other pinned layer is separated by a second tunnel barrier.
20. The bidirectional memory unit according to claim 17 , wherein a state of the second free magnetic layer is detected by sensing a voltage at the free magnetic layer if the third and fourth diodes are forward biased.
In the bidirectional memory cell, based on the earlier description, the state of the read unit's free magnetic layer is determined by sensing the voltage at that free magnetic layer when its corresponding third and fourth diodes are forward biased, allowing current flow for readout.
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August 16, 2016
April 4, 2017
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